Prior art rack mounted rectifiers have been provided for mounting in rectifier cabinets. Such rectifiers have an AC input and a DC output. Rectifier cabinets have found extensive use in the rapidly expanding telecommunications industry, providing power for telephone switch gear and the like. Rectifier cabinets have been provided of modular design, in which rectifier modules are removably mounted within the cabinets. The rectifier modules may be "hot swapped"; that is, a portion of the rectifiers may be removed from the rectifier cabinets without having to shut down the entire cabinet such that power may be maintained for the equipment being powered by the rectifier cabinet being serviced.
Each rectifier module is typically provided with a cooling fan unit, which includes a fan and a motor. The cooling fan unit is required to remove the heat generated by the individual rectifier units included within the rectifier modules. The main cause of failure of the rectifier modules is due to failure of the cooling fan motors. Replacement of fan motors of prior rectifier modules is not easily accomplished in the field; rather, the modules are removed and shipped to a repair facility where fan components are replaced. This requires that spare rectifier modules be available such that rectifier power centers which include a plurality of cabinets need not be taken off-line while failed rectifier modules are being sent to a remote shop for servicing and repair.